The prepositions in, on, and at can be used to indicate time and place. Notice how they are used in the following situations: Preposition Time Place In Year, Month, In 1999, In December Country, State, City In Japan, In Utah, InTaipei On Day, Date On Saturday, On May 1 Street On Main Street, On 1st Ave. At Time At 8:00, At 7:30 Address At 815 East Main Street In many languages, there is only one preposition for the above situations. In English there are three. Just remember that in usually indicates the "largest" time or place, and at usually indicates the "smallest" time or place. "by" can also be a preposition meaning in proximity to , or near Example: I was standing by the window

It is impossible to give a rule about these words. They are best learned in context. But the following pages can help: http://www.englishclub.com/grammar/prepositions-at-in-on-place.htm http://www.englishclub.com/grammar/prepositions-at-in-on-time.htm

You can only work this out by looking at actual examples.

You may look here about using "on, at and in" here: http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv94.shtml "By " is using when you must have done something up by the given time. by 5 o'clock = к пяти часам (что-то должно быть сделано к этому времени)